1. Field of the Invention
The invention relates to time-deinterleavers of a receiver and method for processing input signal thereof, and more particularly to time-deinterleavers of a receiver with low cost hardware architecture and method for processing an input signal thereof.
2. Description of the Related Art
Digital communications, such as that for digital TV broadcasting systems, commonly rely on interleaving transmitted signals at a transmitter side, and deinterleaving transmitted signals at a receiver side. The process of interleaving is commonly used in digital data transmission technology to protect transmissions from burst errors. Burst errors overwrite a significant amount of bits in a row. If occurring, a typical error correction scheme that anticipates more uniform distribution of burst errors may become overwhelmed. Interleaving is used to help prevent this from happening.
In a communications system, interleavers, often used at the transmitter side, and deinterleavers, often used at the receiver side, together, help to more uniformly spread out local signal variations in channels to improve the overall performance of the communications system. As details of the convolution interleaver and convolutional de-interleaver are well known to those skilled in the pertinent art, further description is omitted here for brevity.
In a digital audio broadcasting (DAB) or a digital terrestrial multimedia broadcasting (DTMB) system, a transmitter interleaves a signal before transmission and a receiver then deinterleaves the interleaved signal received from the transmitter. In the interleaving process, the transmitter sequentially writes transmission data in an interleaver memory, reads the written data in a predetermined sequence, and then transmits the read data. In this interleaving process called the “time interleaving process”, the data is delayed for up to n frames (e.g. 16 frames), so that data input to the interleaver would be distributed over n frames when it is output. Therefore, to time-deinterleave the time-interleaved data, the receiver writes n-frame data in a deinterleaver memory (e.g. a Random Access Memory) and then reads the written data according to a deinterleaving rule matched to the interleaving rule used in the transmitter.
For time deinterleaving, the time-deinterleaver needs a memory with a capacity sufficient to store the n data frames. As the technique advances, the depth of the time-interleavers have becomes larger and larger. In a DTMB system, the depth of the time-interleaver is about 300 us (about 510 orthogonal frequency division Multiplexed (OFDM) symbols). The memory size to store the required deinterleaved data is above 1 M bits. If one symbol input to the deinterleaver is data subjected to 6-8-bit, the deinterleaver requires a 6-8 Mbit memory. This means that the deinterleaver must include a 6-8 Mbit memory, thus, increasing the cost of products made therefrom.